M&P Luna/Luna mix help!

[mamababa]

Hi all, I am looking at getting a Luma for DS but want a 2nd hand one. Any advice re 3 wheels or 4, is one easier to push, more stable etc? TIA

we had the 3 wheeler about 2 years ago, loved it but as dd got near the 15k limit she could tip it, they look different now-more like an oyster so not sure what they are like